How to force configure script to use curl ?

Hi,

I was trying to build Git yesterday on a Ubuntu 14 machine that was missing the package "libcurl4-gnutls-dev" necessary to build the http(s) remote helper [1]. 

Doing just

    ./configure 
    make

built Git without support for the http remote helper, as expected. 

However, doing 

    ./configure --with-curl
    make

did the same; it did not result in an error saying that the curl headers could not be found (which I expected). 

Is there a way to force the configure script to error out if it does not find curl (or any one of the optional dependencies that I happen to need for my build?)

Thanks,

Philippe. 

[1] this is one of the package suggested by the progit book : https://git-scm.com/book/en/v2/Getting-Started-Installing-Git